WO 2007/101764 A1 discloses a device for fluid treatment of a plate-like article comprising a rotary head for holding and rotating a plate-like article around a rotation axis, drive means to suspend and drive the rotary head without contact, the drive means being arranged radially around the rotary head, a substantially cylindrical wall, which is substantially concentric to the rotation axis, wherein the cylindrical wall is arranged between the rotary head and the drive means.
A suitable driving mechanism is described in U.S. Pat. No. 6,485,531. With the herein disclosed active magnetic bearing and drive mechanism the distance of stator to rotor is limited. This results in a low wall thickness. Furthermore such active bearing and drive mechanism may lead to undesired current induction in the integrated circuits of the disc-like article. It is an object of the invention to provide an improved drive mechanism. Another object of the invention is to provide a system, which allows the use of a thicker wall.